2020-06-17 09:18 UTC-0700 ~ Andrii Nakryiko <andriin@xxxxxx>
> Add statements about bpftool being able to discover process info, holding
> reference to BPF map, prog, link, or BTF. Show example output as well.
>
> Signed-off-by: Andrii Nakryiko <andriin@xxxxxx>
> ---
> tools/bpf/bpftool/Documentation/bpftool-btf.rst | 5 +++++
> tools/bpf/bpftool/Documentation/bpftool-link.rst | 13 ++++++++++++-
> tools/bpf/bpftool/Documentation/bpftool-map.rst | 8 +++++++-
> tools/bpf/bpftool/Documentation/bpftool-prog.rst | 11 +++++++++++
> 4 files changed, 35 insertions(+), 2 deletions(-)
>
> diff --git a/tools/bpf/bpftool/Documentation/bpftool-btf.rst b/tools/bpf/bpftool/Documentation/bpftool-btf.rst
> index ce3a724f50c1..85f7c82ebb28 100644
> --- a/tools/bpf/bpftool/Documentation/bpftool-btf.rst
> +++ b/tools/bpf/bpftool/Documentation/bpftool-btf.rst
> @@ -36,6 +36,11 @@ DESCRIPTION
> otherwise list all BTF objects currently loaded on the
> system.
>
> + Since Linux 5.8 bpftool is able to discover information about
> + processes that hold open file descriptors (FDs) against BPF
> + links. On such kernels bpftool will automatically emit this
Copy-paste error: s/BPF links/BTF objects/
> + information as well.
> +
> **bpftool btf dump** *BTF_SRC*
> Dump BTF entries from a given *BTF_SRC*.
>
> diff --git a/tools/bpf/bpftool/Documentation/bpftool-link.rst b/tools/bpf/bpftool/Documentation/bpftool-link.rst
> index 0e43d7b06c11..1da7ef65b514 100644
> --- a/tools/bpf/bpftool/Documentation/bpftool-link.rst
> +++ b/tools/bpf/bpftool/Documentation/bpftool-link.rst
> @@ -37,6 +37,11 @@ DESCRIPTION
> zero or more named attributes, some of which depend on type
> of link.
>
> + Since Linux 5.8 bpftool is able to discover information about
> + processes that hold open file descriptors (FDs) against BPF
> + links. On such kernels bpftool will automatically emit this
> + information as well.
> +
> **bpftool link pin** *LINK* *FILE*
> Pin link *LINK* as *FILE*.
>
> @@ -82,6 +87,7 @@ EXAMPLES
>
> 10: cgroup prog 25
> cgroup_id 614 attach_type egress
> + pids test_progs(2238417)
(That's a big PID. Maybe something below the default max pid (32768)
might be less confusing for users, but also maybe that's just me
nitpicking too much.)
>
> **# bpftool --json --pretty link show**
>
> @@ -91,7 +97,12 @@ EXAMPLES
> "type": "cgroup",
> "prog_id": 25,
> "cgroup_id": 614,
> - "attach_type": "egress"
> + "attach_type": "egress",
> + "pids": [{
> + "pid": 2238417,
> + "comm": "test_progs"
> + }
> + ]
> }
> ]
>
